The major thrust of this study is to elucidate the basis of neoplastic transformation of normal tissues. Two experimental model systems were used in this project: (1) a rat hepatoma induced by chemical carcinogen N,N-2,7-fluorenylene bis-2,2,2-trifluoroacetamide, which has been adapted to tissue culture (HTC cells); and (2) two intracisternal A particles (IAP) containing neoplasms, a plasma cell tumor (MOPC-104E) and differentiated neuroblastoma, also adapted to tissue culture (cell lines N-4, N-18, and NB-2A). Multidisciplinary approaches were required in this investigation. They involve tissue culture, biochemical and biophysical analyses, cytogenetics, immunology and tumor biology. Areas with special emphasis of research effort are: (1) the induction and/or rescue of viral (C-type) genome in chemically induced hepatoma; (2) the causal or temporal involvement of this C-type virus in the carcinogenesis of rat hepatoma; (3) the nature of virus-chemical interaction during the process of co-carcinogenesis; (4) cell regulation of viral gene expression on the genetic level; (5) virus infection and the development of chromosome abnormalities during the process of neoplastic transformation, and (6) integration of viral genome and its localization on host cell chromosome(s).